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Chem, Res. Center Crete, IL – Report of A Validation of LC-MS/MS Method for Folate Analysis
25
Figure 3: Chromatograms of a solvent blank (methanol).
Sodium salt vs. Free Ascorbic acid
In the original AOAC method, the sodium ascorbate rather than ascorbic acid was used. It will not make
any difference in the extraction buffer because the pH was adjusted to 6.0 using sodium hydroxide. However, for
the SPE elution solvent and final injection solvent, the pH was not adjusted. A small test of the elution solvent
made from both sodium ascorbate and ascorbic acid (formic acid/methanol/ascorbate v/v/w 10:90:1) was carried
out. The SPE eluates from the two elution solvent gave the same response and made no difference for both the
peak shape and intensity. Actually, the formic acid concentrations in the solvent were so high that the minimum
amount of sodium cannot affect the solvent acidity, which is the most important factor for a anion exchange
procedure in the SPE. The chromatograms from both of the treatments are presented in Figures 8 and 9.
XICof +MRM(14pairs): 442.200/295.200DaID: FA-295fromSample17(Solvent ) of HSST3_121130_01.wiff (TurboSpray)
Max. 60.0cps.
4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8
2 18 33 49 64 80 96 111 127 142 158 173 189 205 220 236 251 267 283 298
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In te n sity, cp s
2011.06 (Fol-22) w/SLV
FOR ERP USE ONLY
DO NOT DISTRIBUTE